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從零手刻 PHP MVC 框架核心架構設計思路

編輯：PHP 相關知識

極簡 MVC 實作四步驟

理解框架核心運作原理，有助於深度使用現有框架或針對特殊需求自研輕量方案。

1. 自動載入機制 (PSR-4)

<?php
spl_autoload_register(function ($class) {
    $baseDir = __DIR__ . '/src/';
    $file = $baseDir . str_replace('\\', '/', $class) . '.php';
    if (file_exists($file)) require $file;
});

// 命名空間對應目錄結構
// src/
//   Controllers/
//   Models/
//   Views/
//   Core/
//   Helpers/

2. 單一入口與路由解析

<?php
// public/index.php
require __DIR__ . '/../vendor/autoload.php';

$requestUri = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
$path = trim($requestUri, '/');
$segments = $path ? explode('/', $path) : [];

// 預設值
$controllerName = $segments[0] ?? 'Home';
$actionName = $segments[1] ?? 'index';
$params = array_slice($segments, 2);

// 命名空間映射
$controllerClass = "App\\Controllers\\{$controllerName}Controller";

if (!class_exists($controllerClass)) {
    http_response_code(404);
    exit('Controller not found');
}

$controller = new $controllerClass();
$method = 'action' . ucfirst($actionName);

if (!method_exists($controller, $method)) {
    http_response_code(404);
    exit('Action not found');
}

// 反射自動綁定參數 (進階)
$refMethod = new ReflectionMethod($controller, $method);
$args = [];
foreach ($refMethod->getParameters() as $param) {
    $name = $param->getName();
    $args[] = $_GET[$name] ?? $_POST[$name] ?? ($param->isDefaultValueAvailable() ? $param->getDefaultValue() : null);
}

$response = $refMethod->invokeArgs($controller, $args);

// 統一回應輸出
if ($response instanceof Response) {
    $response->send();
} elseif (is_string($response)) {
    echo $response;
}

3. 視圖層實作 (作用域隔離 + 資料共享)

<?php
// Core/View.php
class View
{
    private $file;
    private $data = [];
    
    public function __construct(string $file, array $data = [])
    {
        $this->file = $file;
        $this->data = $data;
    }
    
    public function render(): string
    {
        // 擷取變數至區域作用域
        extract($this->data, EXTR_SKIP);
        
        // 開啟輸出緩衝捕獲內容
        ob_start();
        include $this->file;
        return ob_get_clean();
    }
    
    // 魔術方法支援 $view->var 語法
    public function __get($name) { return $this->data[$name] ?? null; }
    public function __set($name, $value) { $this->data[$name] = $value; }
}

// Controller 使用
class PostController
{
    public function actionView($id)
    {
        $post = Post::find($id);
        $view = new View(__DIR__ . '/../Views/post/view.php', [
            'post' => $post,
            'title' => $post->title,
        ]);
        return new HtmlResponse($view->render());
    }
}

4. 回應物件多型設計

<?php
// 回應基類
abstract class Response
{
    abstract public function send(): void;
}

// HTML 回應
class HtmlResponse extends Response
{
    private $content;
    public function __construct(string $content) { $this->content = $content; }
    public function send() {
        header('Content-Type: text/html; charset=UTF-8');
        echo $this->content;
    }
}

// JSON 回應
class JsonResponse extends Response
{
    private $data;
    public function __construct($data, int $status = 200) { 
        $this->data = $data; 
        http_response_code($status);
    }
    public function send() {
        header('Content-Type: application/json; charset=UTF-8');
        echo json_encode($this->data, JSON_UNESCAPED_UNICODE);
    }
}

// 重導向回應
class RedirectResponse extends Response
{
    private $url;
    public function __construct(string $url, int $status = 302) { 
        $this->url = $url; 
        http_response_code($status);
    }
    public function send() {
        header("Location: {$this->url}");
    }
}

// Controller 回傳不同回應
class ApiController
{
    public function actionList()
    {
        return new JsonResponse(['items' => Item::all()]);
    }
    
    public function actionCreate()
    {
        Item::create($_POST);
        return new RedirectResponse('/items');
    }
}